Obstruction sensor for pneumatic door operator

ABSTRACT

A differential pneumatic door actuator, including pneumatic and electrical controls wherein the actuator is drivingly connected to a door and provided with large and small air cylinders, and a pressure responsive switch monitors the pressure in the large cylinder to actuate a reversing cycle relay when a given pressure is detected during the closing cycle.

[ Nov. 4, 1975 I United States Patent 1191 Daugirdas 1 OBSTRUCTION SENSOR FOR PNEUMATIC 1,557,684 10/1925 Gottschalk..............................49/27 49/24 1,849,516 3/1932 Forman..-.............. 2,782,028 2/1957 DOOR OPERATOR [75] Inventor:

Kristupas Daugirdas, Wilmette, 111.

[73] Assignee: Vapor Corporation, Chicago, 111. Primary EXaminer-Kenneth Downey Filed Attorney, Agent, or FirmFrancis J. Lidd Aug. 26, 1974 [57] ABSTRACT A differential pneumatic door actuator, including [21] Appl. No.: 500,575

pneumatic and electrical controls wherein the actuator is drivingly connected to a door and provided with large and small air cylinders, and a pressure responsive switch monitors the pressure in the large cylinder to actuate a reversing cycle relay when a given pressure is detected during the closing cycle.

2mm. WM 4 F 1 u 7 mmn 9 m" {Wm 00 sf Umm HUN 555 [56] References Cited UNITED STATES PATENTS 1,134,608 4/1915 Gottschalk.............................. 49/27 9 Claims, 4 Drawing Figures US. Patent Nov. 4, 1975 Sheet 2 of 2 3 Magnetic Valve Relay Reversing Pressure 42 A Switch FIC5.4 55 H I [fighss E54 52 so 5I/ Air ()BSTRUCTION SENSOR FOR PNEUMATIC DOOR OPERATOR This invention relates in general to pneumatic door operators for opening and closing doors in a vehicle or a building, and more particularly to an obstruction sensor for a differential pneumatic door engine.

The present invention is particularly concerned with door actuating systems where the doors are power driven between open and closed positions in relation to doorways through which persons are moving between the inside and outside of a vehicle, a building, or the like.

It has been well known to provide obstruction sensors for door operators which reverse the closing cycle to open a door or which otherwise stop a closing cycle. It has also been well known to utilize pneumatic door engines in door operators. In recent years, increased emphasis on more efficient operation of mass transit vehicles has made entry and exit of passengers a critical operation. Door systems have become highly complicated and require more rapid door operation to satisfy these requirements, door operators are necessarily designed to generate greater forces in order to achieve the higher door speeds.

Possibilities for injury to passengers passing through the newer door system are substantially increased by rapid operation and greater force characteristics. For example, a passenger can be struck by the moving door edge, and may be injured at the point of contact or in a subsequent fall from the vehicle. A more serious situation arises when a passenger is caught in the door and dragged as the vehicle begins to move.

These factors have placed increased emphasis on obstruction sensing in order to allow door operation in a reasonable time while minimizing possibilities for injury to passengers. This is best done by rapidly sensing the buildup or rate of change of force due to an obstruction in the door path and quickly removing the force by reversing the door motion.

The present invention concerns an obstruction sensor for a differential pneumatic door engine of the well known type such as shown in U.S. Pat. No. 1,849,516. It has also been well known to provide obstruction sensors for such an engine responding to engagement between an obstruction and the door edgeswhich actuate controls, such as in U.S. Pat. No. 2,832,588. It is further known to provide door edges with electrical switches connected in the controls for a pneumatic door engine. All such door edge sensors require connections with the door engine controls.

The present invention provides an obstruction sensor for a differential pneumatic engine which is built into the controls of the engine and remote from the door edge and depends only on the force-time relationship of the door during the closing cycle when an obstruction is encountered. More specifically, a pressure sensing switch monitors the closing pressure of an engine during a door closing cycle such that when the closing pressure rises above a given level due to the door encountering an obstruction, activation of the pressure sensing switch causes the door to stop and move to a fully open or partially open position as desired before again commencing the closing cycle.

It is therefore an object of the present invention to provide an improved obstruction sensor for a differential pneumatic door engine which responds to the closing pressure of the engine during the closing cycle.

Another object of the present invention is to provide a door obstruction sensor for a differential pneumatic door engine wherein the pressure of the large cylinder is monitored during the closing cycle and, if rising to a given value, will actuate a pressure responsive switch to reverse the movement ofthe door and in so doing limit the closing force developed by the door edge in both magnitude and duration. greatly reducing possibilities of injury to passengers who might be struck or caught by the door during the closing cycle.

Other objects, features and advantages of the invention will be apparent from the following detailed disclosure, taken in conjunction with the accompanying sheets of drawings. wherein like reference numerals refer to like parts. in which:

FIG. 1 is a somewhat diagrammatic view of a door engine operating a door and which includes the obstruction sensor according to the present invention.

FIG. 2 is a piping schematic diagram of the pneumatic controls for the door engine shown in FIG. 1;

FIG. 3 is an electrical schematic diagram of the controls for the door engine; and

FIG. 4 is a piping schematic diagram of the pneumatic controls for a pair of door engines operating biparting doors.

Referring now to the drawings and particularly to FIG. 1, a door 10 is illustrated as being suspended from a track 11 for sliding movement therealong in a side wall 12 of a vehicle or building having an opening I3. A differential pneumatic door engine 17 is illustrated as being mounted laterally of the door opening for driving the door 10 between open and closed positions.

The door engine 17 is of the well known type as shown in U.S. Pat. No. 1,849,516, wherein it includes large and small cylinders 18 and I9 and an output shaft 20 driven by the cylinders. The output shaft is suitably drivingly connected to the door 10, wherein it includes a lever arm 21 connected at one end to the shaft 20 and provided with a roller 22 at the other end engaging in a vertical track 23 connected to the trailing edge of the door 10. The position of the lever arm 21, as shown in solid lines. disposes the door I 0 in closed position relative the opening 13 and, as shown in dotted lines. where the arm has oscillated counterclockwise disposes the door in open position relative to the door opening.

The invention concerns "the door leading edge encountering an obstruction. during the closing cycle. so that the door closing cycle can be reversed to prevent injury to the obstruction or damage to the door operating system. especially where it may be a person, and where reversing the closing cycle will allow the person to move from the path of the door before the door is driven through another closing cycle. The obstruction sensor of the invention is builtinto the controls for the door engine such that there is no need to mount any detector in the leading edge of the door.

The pneumatic piping circuit for the door engine 17 and applicable for the installation shown in FIG. 1 is illustrated diagrammatically in FIG. 2, wherein a suitable air supply or source 27 is directly connected to the small cylinder 19 by a line 28. The large cylinder 18 is connected through a line 29 to a three-way normally open magnet valve 30, which is in turn connected through a speed control valve 31 and line 32 to the air supply 27. The closing speed of the engine may be adjusted by the speed controlvalve. A pressure switch 33 is connected to the line 29, thereby monitoring the pressure in the large cylinder 18. The manner in which the well known differential engine 17 operates is conventional in that when the magnet valve 30,.which includes a port 30a connected to the speed COHIIOlKVZ'lYQ,

a port 3012 connected to the line 29-and the large cylin der 18 and port 300 connected to atmospheleis deenergized as illustrated in FIG. 2, ports 30a and 301) are connected to interconnect the air supply to the large cylinder 18 which overcomes the force generated in the small cylinder 19 to either cause a closing cycle if the door had been in open position or to maintain the door in closed position, as illustrated by the parts in solid lines in FIG. 1. Energization of the magnet valve 30 interconnects the port 30b to port 300 for exhausting the air pressure from the large cylinder 18 wherein the force generated in the small cylinder 19 will cause a door opening cycle. During the closing cycle when the magnet valve is de-energized, as illustrated in FIG. 2, should the door encounter an obstruction sufficient to cause the pressure in the large cylinder to rise above a given point accordingto the adjustment'of the pressure switch 33, the pressure switch 33 will be activatedto cause the reversing cycle as will be niore clea r following the description of the electrical diagram'in FIG 3. While the pressure switch may be adjusted toactiv'at e or trigger at any given level, it is preferably set totrigger at about sixty percent of the linepressure from the air supply. I Y 1 Referring now to FIG. 3, an electrical schematic diag't'am for controlling the magnet valveis illustrated which includes a suitable power supply connected across lines 37 and 38. The magnet valve 30 is connected at one end to line 38 and at the other end to a manually operable'door control line 39, having a switch 40 which, when closed, will energize the magnet valve and cause a door opening cycle and which, opened, will de-energize the magnet valve'a nd cause a door closing cycle. f l z i A reversing relay 41 is connected to cause energization of the magnet valve 30 and reversal of the door closing cycle in the event the pressure switch 33 is triggered during a door closing cycle. The relay is connected at one end to the line 38 and at the other end to the pressure switch line 42 having the pressure switch 33 and a limit switch 43 therein. The limit switch 43 is suitably actuated by a cam (not shownlon the output shaft of the door engine such that the limit switch is open, as illustrated when the doors are in closed position, to prevent the pressure switch 33 with its closed contacts from triggering the reversing relay, as the pressure in the large cylinder will build up to line pressure when the door is in closed position. During the opening cycle of the door, when the pressure in the large cylinder is exhausted to atmosphere, the pressure switch will open and the limit switch 43 will be closed. Accordingly, the limitswitch 43 will be closed during the closing cycle of the door until the door reaches fully closed position when it will then open.

,The reversing relay 41 includes switch contacts4la and 41b. Contacts 41a are in a reversing Iine44, while contacts 41b are in a stick circuit" line 45. Additionally, limit switch 46 is in line 45 and operable, to open when the door reaches fully open position or any partial open position if desired.

The contacts shown in FlG..3 are illustrated in their positions whenE-the door is fully closed. In operation, normal opening and closing of the door is accomplished by actuation ofthe switch 40.for, energizing the magnet valve- 30 to cause an, opening cycle and deenergizing the magnet valveto cause a closing cycle.

When the doorsare infullyopened position and normally d uringthe closing cycle; the limit switch 43 will be closed and thepressure switch contacts will be open. During the closing cycle. the pressure in the large cylinder is less than line pressure and less than that which would causetriggering of the pressure switch due to the pressure drop across the speed control valve. The limit switch c onta cts 46 would be open at the full open position or any piartial open position as desired. During the closing cycle when theswitch 40 is open, should an obstruction be encountered by the door thereby stopping or nearly st'opping the door in the closing cycle, pressure will build up in the large cylinder 18 and at the given pressure value of the pressure switch 33 cause triggering of the pressure switch to close the contacts andene rgize the reversing relay '41 to reverse the clos- -ing cycle ar d causejthe'door to move toward the open osition The forces produced at the door edge, when e'ncouhtering ah obstacle, therefore, have a controlled. buildup and can easily be held to a safe maximum valiie'l Also, theduration of the peak force is onlya few milliseconds since 'the reversal relay and magnetic valve 30 operate in milliseconds to exhaust the large cylinder and open the door. It can" beappreciated that since chances of injury to passengers struck by or caught in the door while exiting a vehicle is greatly minimized by the rapid decrease of door edge forceJ'Energization of the reversing relay energizes the magnet valve 30 toex h'au's't the jair from the-large cylinder 18 whereby the pressure in the'sm'all'c'ylinder' l9will cause the opening cycle. The contacts 4112 close thestick circuit line '45 so'that as the pressute'switch releases and opens'its coiitacts in the opening cyclefthe "reversing relay will be maintained in energized position to continue the opening cycle until the limit switch 46 is opened. Thereafter, de-energization of the reversing relay and the magnet-valve will again allow the door to moveto closed position. If the obstruction is then removed from the path of the'doonit will continue until it 'is in fully closed position. a

It -will be appreciated the controls for sensing the obstruction, while described above as applicable to a single door engine fora. single door, can also be applied to biparting doors where each is driven by-a door engine. A piping diagram illustrating the pneumatic circuit for such an arrangment is illustrated in. FIG. 4 wherein door engines 50 and 51 have their small cylinders connected directly-to an air supply- 52 and their large cylinders connected to the air supply through flow control valves 53 and 54 and a three-way normally open magnet valve.55. The flow control valves 53 and 54. are essentially the same asthe speed control valve 31 in-the embodiment of FIG. 2-, while the magnet valve 55' is essentially-the same-asthat illustrated in the embodimentof FIG. 2. Pressure sensing switches 56 and 57 respectively monitor the pressure in the' large cylinders of the door engines 50 and 51 The circuit of FIG. 3 would ,bemodifiedby merely including another pres- I sure switch. lin'efor the additional pressure'switch and which would be in parallel with the pressure switch line 42. A limit switchwould also be providedin the addithat one of the pressure-switch lines would relate to the pressure switch 56, while the other would relate to the pressure switch 57. Further, it can be appreciated that the door engines would operate together pursuant to the operation of the single magnet valve 55 and should one of the biparting doors sense an obstruction thereby triggering one of the pressure switches, the reversing relay would cause the magnet valve to reverse the clos ing cycle of both doors being driven by the door engines 50 and 51. It can be appreciated that any number of door engines may be included responding to a single magnet valve and for obstruction sensing a pressure switch would monitor the pressure in each of the large cylinders of the door engines.

It may be appreciated that adjustment of the pressure switches will permit reversal of the door closing cycle responsive to any given obstruction force. Preferably, the switch is adjusted to close and reverse the door closing cycle when the pressure in the large cylinder of the engine is approximately sixty percent of available line pressure. It may therefore be seen that the present invention provides a foolproof and economical arrangement for sensing door obstruction and reversing the door closing cycle.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention, but it is understood that this application is to be limited only by the scope of the appended claims.

The invention is hereby claimed as follows:

1. In a system for operating a door between open and closed positions and reversing a door closing cycle upon sensing an obstruction at the door, a differential pneumatic door engine having large and small cylinders and an output shaft driven by the cylinders and drivingly connected to the door, an air supply, means connecting the air supply directly to the small cylinder, an electrically operable valve for selectively interconnecting the large cylinder to the air supply to close the door or to atmosphere to open the door, flow control means between the air supply and the large cylinder, a normally open pressure switch monitoring the pressure in the large cylinder and responding to an obstruction encountered by the door, a reversing cycle relay having contacts for operating the valve to interconnect the large cylinder to atmosphere, and said pressure switch having contacts for operating said relay to close the valve contacts and cause the valve to interconnect the large cylinder to atmosphere for a door opening cycle, wherein said pressure switch and said flow control means coact with each other to respond to a predetermined pressure in the large cylinder caused by an obstruction encountered by the door.

2. In a system as defined in claim 1, which further includes means for disabling the pressure switch when the door is in closed position.

3. In a system as defined in claim 2, which further includes means for maintaining the relay conditioned to hold the valve contacts closed until the door has opened to a predetermined position.

4. In a system for operating a door between'open and.

closed positions and reversing a door closing cycle upon sensing an obstruction at the door, a differential pneumatic door engine having large and small cylinders and an output shaft drivingly connected to the door, an air supply connected directly to the small cylinder, a

two-position three-way normally open exhaust-type magnet valve having a first port connected to the large cylinder, asecond port connected to the air supply, and

a third port connected to atmosphere, wherein the valve when de-energized interconnects said first'and second ports causing the engine to close the door and 'when energized interconnects said first and third ports causing the engine to open the door. a normally open pressure switch connected to monitor the pressure of said large cylinder, flow control means between said air supply and said valve, a reversing cycle relay having contacts for energizing the magnet valve, and said pressure switch having contacts for energizing said relay upon detecting a given pressure in the large cylinder during the door closing cycle, wherein said pressure switch and said flow control means coact with each other to respond to a predetermined pressure in the large cylinder caused by an obstruction encountered by the door.

5. In a system for driving a door between open and closed positions having a differential pneumatic door engine, an air supply for driving said engine, said engine having an output shaft and large and small cylinders driving said shaft, and means drivingly connecting the outputshaft to the door, the improvement being in control means for said engine which senses a door obstruction and reverses the door closing cycle, said control means including means connecting the small cylinder directly to the air supply, a three-way magnet valve connected between the air supply and large cylinder interconnecting the large cylinder to the air supply when de-energized to cause a door closing cycle and to the atmosphere when energized to cause a door opening cycle, a reversing cycle relay having normally open contacts which close upon energization thereof to cause energization of the magnet valve, a pressure sensing switch monitoring the pressure in the large cylinder having contacts which close in response to a given pressure to cause energization of the reversing relay, and flow control means between the air supply and the large cylinder, wherein said pressure switch and said flow control means coact with each other to respond to a predetermined pressure in the large cylinder caused by an obstruction encountered by the door.

6. In a system as defined in claim 5, wherein said control means further includes a limit switch in series with the contacts of the pressure sensing switch, and means for opening the limit switch when the door reaches fully closed position.

7. In a system as defined in claim 6, wherein said control means further includes a stick circuit" having contacts which close upon the energization of the reversing relay and a normally closed limit switch and means for opening same during the door opening cycle to de-energize the reversing relay and cause a door closing cycle.

8. In a system as defined in claim 7, wherein the pressure sensing switch is set to operate and close its contacts in response to detection of about sixty percent line pressure.

9. In a system for driving a door between open and closed positions having a differential pneumatic door engine, an air supply for driving said engine, said engine having an output shaft and large and small cylinders driving said shaft, and means drivingly connecting the output shaft to the door, the improvement being in control means for said engine which senses a door obstruction. limits the door edge force in accordance with means monitoring the pressure in the large cylinder for controlling operation ot'said valve means, whereby said pressure responsive means and said orifice means coact with each other to respond to a predetermined pressure in the large cylinder caused by an obstruction encountered by the door. 

1. In a system for operating a door between open and closed positions and reversing a door closing cycle upon sensing an obstruction at the door, a differential pneumatic door engine having large and small cylinders and an output shaft driven by the cylinders and drivingly connected to the door, an air supply, means connecting the air supply directly to the small cylinder, an electrically operable valve for selectively interconnecting the large cylinder to the air supply to close the door or to atmosphere to open the door, flow control means between the air supply and the large cylinder, a normally open pressure switch monitoring the pressure in the large cylinder and responding to an obstruction encountered by the door, a reversing cycle relay having contacts for operating the valve to interconnect the large cylinder to atmosphere, and said pressure switch having contacts for operating said relay to close the valve contacts and cause the valve to interconnect the large cylinder to atmosphere for a door opening cycle, wherein said pressure switch and said flow control means coact with each other to respond to a predetermined pressure in the large cylinder caused by an obstruction encountered by the door.
 2. In a system as defined in claim 1, which further includes means for disabling the pressure switch when the door is in closed position.
 3. In a system as defined in claim 2, which further includes means for maintaining the relay conditioned to hold the valve contacts closed until the door has opened to a predetermined position.
 4. In a system for operating a door between open and closed positions and reversing a door closing cycle upon sensing an obstruction at the door, a differential pneumatic door engine having large and small cylinders and an output shaft drivingly connected to the door, an air supply connected directly to the small cylinder, a two-position three-way normally open exhaust-type magnet valve having a first port connected to the large cylinder, a second port connected to the air supply, and a third port connected to atmosphere, wherein the valve when de-energized interconnects said first and second ports causing the engine to close the door and when energized interconnects said first and third ports causing the engine to open the door, a normally open pressure switch connected to monitor the pressure of said large cylinder, flow control means between said air supply and said valve, a reversing cycle relay having contacts for energizing the magnet valve, and said pressure switch having contacts for energizing said relay upon detecting a given pressure in the large cylinder during the door closing cycle, wherein said pressure switch and said flow control means coact with each other to respond to a predetermined pressure in the large cylinder caused by an obstruction encountered by the door.
 5. In a system for driving a door between open and closed positions having a differential pneumatic door engine, an air supply for driving said engine, said engine having an output shaft and large and small cylinders driving said shaft, and means drivingly connecting the outputshaft to the door, the improvement being in control means for said engine which senses a door obstruction and reverses the door closing cycle, said control means including means connecting the small cylinder directly to the air supply, a three-way magnet valve connected between the air supply and large cylinder interconnecting the large cylinder to the air supply when de-energized to cause a door clOsing cycle and to the atmosphere when energized to cause a door opening cycle, a reversing cycle relay having normally open contacts which close upon energization thereof to cause energization of the magnet valve, a pressure sensing switch monitoring the pressure in the large cylinder having contacts which close in response to a given pressure to cause energization of the reversing relay, and flow control means between the air supply and the large cylinder, wherein said pressure switch and said flow control means coact with each other to respond to a predetermined pressure in the large cylinder caused by an obstruction encountered by the door.
 6. In a system as defined in claim 5, wherein said control means further includes a limit switch in series with the contacts of the pressure sensing switch, and means for opening the limit switch when the door reaches fully closed position.
 7. In a system as defined in claim 6, wherein said control means further includes a ''''stick circuit'''' having contacts which close upon the energization of the reversing relay and a normally closed limit switch and means for opening same during the door opening cycle to de-energize the reversing relay and cause a door closing cycle.
 8. In a system as defined in claim 7, wherein the pressure sensing switch is set to operate and close its contacts in response to detection of about sixty percent line pressure.
 9. In a system for driving a door between open and closed positions having a differential pneumatic door engine, an air supply for driving said engine, said engine having an output shaft and large and small cylinders driving said shaft, and means drivingly connecting the output shaft to the door, the improvement being in control means for said engine which senses a door obstruction, limits the door edge force in accordance with the resistance of the obstruction before the large cylinder develops maximum force and reverses the door closing cycle, said control means including orifice means between said air supply and said large cylinder, valve means for selectively interconnecting the large cylinder to the air supply to close the door or to atmosphere to open the door, and a pressure responsive means monitoring the pressure in the large cylinder for controlling operation of said valve means, whereby said pressure responsive means and said orifice means coact with each other to respond to a predetermined pressure in the large cylinder caused by an obstruction encountered by the door. 